I think Ukraine has let it go. They want to build a nation state and don’t need an enclave that does not harmonize with them. The troubling part in all this is not that Russia got Crimea but that the Russian Federation did it in the worst possible way for itself, its citizens and its standing in the world.
Annexation of Crimea was inevitable.
The big question is Putin. Is he willing to stop now and allow his successors to continue the task of reassembling the Russian empire, which would be the wisest course of action?
Or will Putin - as did Hitler - push until he arrays all the nations of the world against him?
That is, does Putin know how to stop? Stopping is very difficult for leaders; only the really great ones such as Bismark know how to do it.
Its true that the RF has taken a hit, but hits such as Crimea are soft. The RF can recover from it. If Putin stops, within a year no one will remember the Crimea. Annexation will be seen as inevitable, though lamentable.
If Putin stops.